Micafungin is the active pharmaceutical ingredient in Mycamine®. According to the FDA label, the chemical structure of Micafungin sodium is represented by formula (I):

Micafungin is also known as Pneumocandin A0, 1-[(4R,5R)-4,5-dihydroxy-N2-[4-[5-[4-(pentyloxy)phenyl]-3-isoxazolyl]benzoyl]-L-ornithine]-4-[(4S)-4-hydroxy-4-[4-hydroxy-3-(sulfoxy)phenyl]-L-threonine]. Micafungin sodium is furthermore known as FK-463. The assigned Registry No's by Chemical Abstracts are 235114-32-6 for Micafungin and 208538-73-2 for Micafungin sodium.
Micafungin is an echinocandin which inhibits 1,3-β-D-glucan synthase and thus leads to fungal cell lysis. Micafungin is thus useful as an antifungal agent in the treatment of infections caused by strains of e.g. Aspergillus, Cryptococcus, Candida, Mucor, Actinomyces, Histoplasma, Dermatophyte, Malassezia, and Fusarium. Micafungin is the active ingredient in the approved drugs Mycamine® and Funguard® which are used in the treatment and prophylaxis of infections caused by Candida. 
Various methods for the preparation and purification of Micafungin are known to the skilled person, see e.g. U.S. Pat. No. 6,107,458 and U.S. Pat. No. 7,199,248. More particularly, U.S. Pat. No. 7,199,248 discloses a method wherein a crude DIPEA salt of Micafungin is purified by filtration and chromatographic separation using a regenerated γ Alumina in a 1350-L column and eluting Micafungin DIPEA with Methanol. The Micafungin containing fraction is further purified and transferred to a sodium salt of Micafungin, inter alia by ion exchange chromatography using a regenerated ion exchange resin UBK510L. Micafungin sodium is eluted with aqueous Methanol. Acetone and ethyl acetate is finally used for precipitation of Micafungin sodium.
It is well known in the art that the diisopropylethylamine (DIPEA) salt of Micafungin is more stable than the sodium salt of Micafungin. Therefore, the prior art methods as the method disclosed above often make use of the DIPEA salt as an intermediate when preparing Micafungin sodium. This is e.g. described in the General Thesis, “Process Development of Micafungin, a Novel Lipopeptide Antifungal Agent” by Ohigashi et al. in Journal of Synthetic Organic Chemistry, Japan, vol. 64, No. 12, December 2006. In Ohigashi et al., a method is disclosed wherein impurities present in a DIPEA salt of Micafungin are removed by the use of resins. The DIPEA salt purified by the use of an alumina resin column is according to Ohigashi et al. then subjected to ion exchange chromatography for converting the DIPEA salt of Micafungin to a sodium salt of Micafungin.
It is clear that the prior art methods for the preparation of Micafungin sodium as mentioned above involves two consecutive chromatography steps, i.e. firstly the purification of Micafungin DIPEA on a Reverse Phase Chromatography (RPC) resin and secondly the transformation of the DIPEA salt to the sodium salt, i.e. a salt swap, on a ion-exchange resin. The use of two subsequent chromatography steps for the obtainment of the desired sodium salt of Micafungin is labor-intensive and the providing of an improved method involving fewer processing steps, less chemicals and equipment would be beneficial both from an economical aspect as well as from an environmental and labor-saving point of view.
It is thus still a need for more efficient processes for the preparation of a purified Micafungin and derivates thereof, such as the sodium salt of Micafungin.